Printers typically print by depositing a consumable opaque substance on a page, such as toner deposited on a printed page in a laser printer or ink deposited on a printed page in an inkjet printer. Such consumables are replaced on a periodic basis as they are depleted, and are desirably user-replaceable or serviceable items. Laser printers, for example, typically have toner cartridges containing toner that a user can easily remove and replace. Similarly, inkjet printers typically have ink cartridges that a user can remove and replace.
Because printer users usually replace consumables such as toner cartridges, ink cartridges, and paper themselves, it is often up to the user of the printer to shop for and acquire replacement consumables when a printer's supply is depleted. As with any commodity item, the consumer is likely to select a replacement based on perceived quality and on cost. Even when a manufacturer's consumable product is to be purchased to ensure quality and compatibility, pricing can vary significantly from vendor to vendor and make price comparison worthwhile.
Certain Internet web sites enable consumers to seek out the lowest prices on various printer-related consumable items such as paper, ink cartridges, and toner cartridges, but they require a manual search and evaluation of the results to determine to what extent they meet a consumer's needs. They also require a user to actively seek out prices on a periodic basis, check a variety of sources, and keep track of and analyze the discovered information.